I've never met a quant trader trading for their own account. It requires some infrastructure that would be hard to justify unless you have lots of money to invest, and you're really good at it.
It is common for successful quant traders to be partners (have equity) in their firms, which means they are "trading for their own account" to some extent.
I think what he meant by "for their own account" was something smaller and personal. Not part of a larger pool containing hundreds of millions of dollars.